Japanese onsen are natural hot springs, born from the country’s plentiful volcanic activity. (Antony Giblin/LPI/Getty)

Hot baths, saunas, steam rooms, hot springs – spa culture takes on various forms throughout the world, and learning to relax like a local is a top attraction in many destinations. But as entwined as bathhouse culture has become with many modern day societies, the seemingly omnipresent practice of using heat to release toxins is actually tens of thousands of years old, dating back to the Neolithic Age when nomadic tribes would find relief from the bitter cold by soaking in the various natural hot springs they stumbled upon around the world.

One of the world’s earliest known public baths was built in the Indus Valley around 2500 BC in the lost city of Mohenjo-daro. Called the “Great Bath”, this large pool constructed of baked brick was excavated in the early 1900s by archaeologists in present-day Pakistan. Anthropologists say it may have been used as a temple, since bathing and cleanliness may have been linked to religious beliefs.

Much later, around 300 BC, the practice of public bathing was adopted by the Romans, and the bath became a vital part of society, visited by rich and poor. For many it was the only place to rinse off after a long week of manual labour and at the time, crowds of men and women bathed naked together, as the bath was a primary place to gather and socialize.

The tradition of the public bath has since spread around the world, adapting to evolving cultures and social norms with differing customs and etiquette for each destination.

Turkish hammamTurkish baths, called hammams, were likely derived in part from Roman and Byzantine baths -- an export of the Roman Empire that extended to Turkey in the 7th Century. The concept was predicated on having places of extreme cleanliness, where purifying the body went hand-in-hand with purifying the soul. Popularized around 600 AD, hammams were also spaces where major life events were celebrated, and bathing rituals were incorporated into weddings and births.

The hammam is still a common gathering place for socializing and relaxing today. Upon entering, visitors may be given a towel, a pair of sandals and an abrasive mitt, a keşe -- meant for exfoliating the skin. The hammam typically consists of three main areas: a hot steam room with a large marble stone at the centre, where bathers lay as attendants scrub them and administer massages; a warm room for bathing; and a cool room for resting. Areas are typically gender-separated and nudity is optional.

One historic hammam worth visiting is Istanbul's Cagaloglu Hamami, a palatial marble bathhouse that was built in 1741.

Russian banyaEarly historical accounts place the Russian banya, or bathhouse, in a central societal role by the 900s. In Slavic mythology, there was even a banya spirit, named Bannik, who was believed to hide under bathhouse benches, only to reveal himself if a visitor was disrespectful or misbehaved -- in which case, Bannik would throw boiling water or hot rocks at the disruptive bather.

Throughout Russian history, the banya has been enjoyed by all classes. Villagers who did manual labour used to visit a public bathhouse, often the only place to wash off, while wealthy Russians would sometimes indulge in private banyas. Bathhouses were also visited as a spiritual experience, often on Sundays, a tradition that continues today. The act of bathers hitting themselves with bunches of birch twigs called veniki, for example, is with the intended purpose of opening pores and increasing circulationas well as an act of self-flagellation.

Today, most banyas are gender separated and nudity is optional. They typically include a cold plunge pool and a hot steam room with wooden benches at varying heights -- the higher you go, the hotter the steam gets.

One of the oldest banyas in Moscow (and one of the most famous) is Sanduny Banya, built in 1806. It’s a large complex today, with swimming pools, a fitness centre, a beauty salon and a restaurant.

Japanese onsenJapanese onsen are natural hot springs, born from the country’s plentiful volcanic activity, and the practice of soaking in these thermal baths for healing, spirituality and rejuvenation stems back to when Buddhism spread to Japan in the 500s. Some evidence suggests that Buddhist monks had a hand in founding some of the earliest spa-like spots around the country.

Since Japan’s onsen are based around natural formations, some have been around for thousands of years. One such place is Dogo Onsen, located on the island of Shikoku, believed to have been in use for at least 3,000 years. Mentions of the onsen have been found in texts from early Japanese history, illustrating it as the great leveller, welcoming gods, emperors and peasants alike. There is a certain cultural protocol to keep in mind when visiting a Japanese hot spring resort (nudity is required, for example). Before taking the plunge, refer to this guide to onsen etiquette.

Korean jimjilbangDisrobing is also mandatory in jimjilbangs, or Korean bathhouses, which are always separated by gender. Jimjilbangs are a family affair in South Korea, with everyone from children to the elderly joining in on the pastime.

The origins of this tradition could be linked to the country’s natural hot springs, some of which have been in use for more than a thousand years. Today, many jimjilbangs are open 24-hours and offer lodging for the night, perfect for weary travellers. Also unique to Korea are the materials used in the saunas, steam rooms and hot tubs. For instance, jade may be used in the sauna to relieve joint pain and stress, while baked clay may be used to promote detoxification. Body scrubs are also very common, using a mitt similar to the Turkish kese, but with milk and water to moisturize the skin while promoting circulation.

One of the more famous jimjilbangs in Seoul is the massive Dragon Hill Spa, a seven-storey spa featuring a seawater bath, a salt room, saunas, baths, a swimming pool, a fitness centre, gardens, a food court, a nail salon, a golf course, an internet cafe and a movie theatre. The primary draw is the main sauna, heated by charcoal and infused with an oak aroma.

Native American sweat lodgeThe earliest accounts of sweat lodges in Native American culture appear in writings by European settlers from the 1600s, and according to anthropologist Raymond A Bucko, author of The Lakota Ritual of the Sweat Lodge, sweat lodges have not changed significantly since that time. Participants in the sweat ritual gather inside a dome-shaped hut or tent, where a pile of heated rocks lies in the middle. A sweat leader tends to the rocks and may pour water on top to fill the lodge with steam. He also leads the group in prayer and song. During the ceremony, offerings such as tobacco may be made to the spirits.

Unlike other bathhouses, sweat lodge rituals can last up to several hours. There are often multiple 30-minute rounds, with breaks in-between to let the outside air in and drink water.

The Native American sweat experience, a ceremony expressly and wholly focused on the spiritual, pushes both the body and the mind to its limits. Suffering for the sake of moral strengthening is one important theme that permeates throughout the sweat lodge, Bucko explained in his book.

Finnish saunaSaunas are ubiquitous in Finland, a country with around two million saunas, or approximately one sauna for every two or three people. Nearly all Finns “take a sauna” at least once a week (even those in incarceration) and many families own portable saunas to take on camping trips. “Sauna” is even a Finnish word, meaning a hot steam bath -- the steam for which is created by pouring water over heated stones.

Although the origins of the Finnish sauna are murky, Finland’s cold climate likely contributed to the creation of this heat-filled structure. According to the documentary Steam of Life”, a film focused on Finland’s spa obsession, some of the first saunas were heated huts that also served as homes. In addition to bathing, saunas would have been used for chores requiring high heat, such as curing meats, and practices requiring sterile environments, such as preparing to bury the dead.

The traditional Finnish sauna -- which dates back to at least the 12th Century - is a smoke sauna, heated by a wood stove with no chimney. After soaking in the heat, many locals will head outside to roll around in the snow or jump into a hole in a frozen-over lake, since going from hot to cold is thought to stimulate blood circulation.

The oldest public sauna still in use in Finland is the Rajaportin Sauna, a smoke sauna dating back to 1906 and located in the southern city of Tampere. To stay in Finland and not take a sauna would be like visiting Ancient Rome and not stopping at the local bathhouse. What better place to experience this age-old tradition than a historic spa that helped shape the customs of today?